Old Etonian Stewart says the happy couple will drive to the ceremony in his family’s old van then walk home over the fields.

He met astrophysics graduate Shoshana when she moved to Afghanistan with her first husband, charity worker Noah Coburn, to work for the Turquoise Mountain Foundation – a charity set up by Stewart and Prince Charles in 2006.

She became its chief executive a few months after arriving in Kabul and later became managing director.

She worked alongside Stewart on the project for two years before ditching her husband in 2009.

They divorced in 2010 and she moved in with Stewart last September.

Earlier this year, Noah admitted he was “heartbroken” that Shoshana had “dumped me for Mr Stewart”.

But a mutual pal of the couple insisted their romance began after she had separated from Noah.

Stewart was seen as one of the UK’s most eligible bachelors and was named alongside Prince Harry and Robert Pattinson in GQ magazine’s list of the Top 50 men of 2010.

But he is obviously looking forward to the wedding, boasting about it on his blog as he travelled north for the ceremony before deleting the post.

He wrote: “On Monday at eleven, 14 of us will stand in the small low chapel in Scotland – our parents, her brother, my sisters, my nephew, everyone from home, and the vicar.

“And that is basically it. Except perhaps my father’s lurcher Torquil, who may appear in a tartan bow-tie.

“We will go to and from the church in the family’s Vauxhall van and we’ll walk the last section home over the fields.

“It is unclear what the Aberdeen Angus and the Highland cow in the sunken field will make of her wedding dress.”

Stewart was elected MP for Penrith and the Borders in May 2010.

Just two months later he outraged his constituents by calling them “primitives who hold up their trousers with string”.